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java.lang.Object
org.apache.commons.logging.LogFactory
public abstract class LogFactory
extends java.lang.Object
Log
instances, with discovery and
configuration features similar to that employed by standard Java APIs
such as JAXP.
IMPLEMENTATION NOTE - This implementation is heavily
based on the SAXParserFactory and DocumentBuilderFactory implementations
(corresponding to the JAXP pluggability APIs) found in Apache Xerces.
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static String |
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static String |
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static String |
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protected static String | |
protected static Hashtable |
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private static void |
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abstract Object |
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abstract String[] |
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private static LogFactory |
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protected static ClassLoader |
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static LogFactory |
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abstract Log |
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abstract Log |
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static Log |
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static Log |
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private static InputStream |
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protected static LogFactory |
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abstract void | |
static void |
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static void |
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abstract void |
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abstract void |
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public static final String FACTORY_DEFAULT
The fully qualified class name of the fallbackLogFactory
implementation class to use, if no other can be found.
public static final String FACTORY_PROPERTIES
The name of the properties file to search for.
public static final String FACTORY_PROPERTY
The name of the property used to identify the LogFactory implementation class name.
protected static Hashtable factories
The previously constructedLogFactory
instances, keyed by theClassLoader
with which it was created.
public abstract Object getAttribute(String name)
Return the configuration attribute with the specified name (if any), ornull
if there is no such attribute.
- Parameters:
name
- Name of the attribute to return
public abstract String[] getAttributeNames()
Return an array containing the names of all currently defined configuration attributes. If there are no such attributes, a zero length array is returned.
private static LogFactory getCachedFactory(ClassLoader contextClassLoader)
Check cached factories (keyed by contextClassLoader)
protected static ClassLoader getContextClassLoader() throws LogConfigurationException
Return the thread context class loader if available. Otherwise return null. The thread context class loader is available for JDK 1.2 or later, if certain security conditions are met.
- Throws:
LogConfigurationException
- if a suitable class loader cannot be identified.
public static LogFactory getFactory() throws LogConfigurationException
Construct (if necessary) and return aLogFactory
instance, using the following ordered lookup procedure to determine the name of the implementation class to be loaded.NOTE - If the properties file method of identifying the
- The
org.apache.commons.logging.LogFactory
system property.- The JDK 1.3 Service Discovery mechanism
- Use the properties file
commons-logging.properties
file, if found in the class path of this class. The configuration file is in standardjava.util.Properties
format and contains the fully qualified name of the implementation class with the key being the system property defined above.- Fall back to a default implementation class (
org.apache.commons.logging.impl.LogFactoryImpl
).LogFactory
implementation class is utilized, all of the properties defined in this file will be set as configuration attributes on the correspondingLogFactory
instance.
- Throws:
LogConfigurationException
- if the implementation class is not available or cannot be instantiated.
public abstract Log getInstance(Class clazz) throws LogConfigurationException
Convenience method to derive a name from the specified class and callgetInstance(String)
with it.
- Parameters:
clazz
- Class for which a suitable Log name will be derived
- Throws:
LogConfigurationException
- if a suitableLog
instance cannot be returned
public abstract Log getInstance(String name) throws LogConfigurationException
Construct (if necessary) and return aLog
instance, using the factory's current set of configuration attributes. NOTE - Depending upon the implementation of theLogFactory
you are using, theLog
instance you are returned may or may not be local to the current application, and may or may not be returned again on a subsequent call with the same name argument.
- Parameters:
name
- Logical name of theLog
instance to be returned (the meaning of this name is only known to the underlying logging implementation that is being wrapped)
- Throws:
LogConfigurationException
- if a suitableLog
instance cannot be returned
public static Log getLog(Class clazz) throws LogConfigurationException
Convenience method to return a named logger, without the application having to care about factories.
- Parameters:
clazz
- Class from which a log name will be derived
- Throws:
LogConfigurationException
- if a suitableLog
instance cannot be returned
public static Log getLog(String name) throws LogConfigurationException
Convenience method to return a named logger, without the application having to care about factories.
- Parameters:
name
- Logical name of theLog
instance to be returned (the meaning of this name is only known to the underlying logging implementation that is being wrapped)
- Throws:
LogConfigurationException
- if a suitableLog
instance cannot be returned
private static InputStream getResourceAsStream(ClassLoader loader, String name)
protected static LogFactory newFactory(String factoryClass, ClassLoader classLoader) throws LogConfigurationException
Return a new instance of the specifiedLogFactory
implementation class, loaded by the specified class loader. If that fails, try the class loader used to load this (abstract) LogFactory.
- Parameters:
factoryClass
- Fully qualified name of theLogFactory
implementation classclassLoader
- ClassLoader from which to load this class
- Throws:
LogConfigurationException
- if a suitable instance cannot be created
public abstract void release()
Release any internal references to previously createdLog
instances returned by this factory. This is useful in environments like servlet containers, which implement application reloading by throwing away a ClassLoader. Dangling references to objects in that class loader would prevent garbage collection.
public static void release(ClassLoader classLoader)
Release any internal references to previously createdLogFactory
instances that have been associated with the specified class loader (if any), after calling the instance methodrelease()
on each of them.
- Parameters:
classLoader
- ClassLoader for which to release the LogFactory
public static void releaseAll()
Release any internal references to previously createdLogFactory
instances, after calling the instance methodrelease()
on each of them. This is useful in environments like servlet containers, which implement application reloading by throwing away a ClassLoader. Dangling references to objects in that class loader would prevent garbage collection.
public abstract void removeAttribute(String name)
Remove any configuration attribute associated with the specified name. If there is no such attribute, no action is taken.
- Parameters:
name
- Name of the attribute to remove
public abstract void setAttribute(String name, Object value)
Set the configuration attribute with the specified name. Calling this with anull
value is equivalent to callingremoveAttribute(name)
.
- Parameters:
name
- Name of the attribute to setvalue
- Value of the attribute to set, ornull
to remove any setting for this attribute